2 * Copyright (c) 2016 Cisco Systems, Inc. and others. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
8 package org.opendaylight.controller.cluster.access.client;
10 import akka.actor.ActorRef;
11 import com.google.common.annotations.VisibleForTesting;
12 import com.google.common.base.Preconditions;
13 import com.google.common.base.Verify;
14 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
15 import java.util.ArrayDeque;
16 import java.util.Collection;
17 import java.util.Deque;
18 import java.util.Iterator;
19 import java.util.Optional;
20 import java.util.Queue;
21 import org.opendaylight.controller.cluster.access.concepts.Request;
22 import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope;
23 import org.opendaylight.controller.cluster.access.concepts.RequestException;
24 import org.opendaylight.controller.cluster.access.concepts.Response;
25 import org.opendaylight.controller.cluster.access.concepts.ResponseEnvelope;
26 import org.opendaylight.controller.cluster.access.concepts.RuntimeRequestException;
27 import org.opendaylight.controller.cluster.access.concepts.SliceableMessage;
28 import org.opendaylight.controller.cluster.messaging.MessageSlicer;
29 import org.opendaylight.controller.cluster.messaging.SliceOptions;
30 import org.slf4j.Logger;
31 import org.slf4j.LoggerFactory;
34 * This queue is internally split into two queues for performance reasons, both memory efficiency and copy
38 * Entries are always appended to the end, but then they are transmitted to the remote end and do not necessarily
39 * complete in the order in which they were sent -- hence the head of the queue does not increase linearly,
40 * but can involve spurious removals of non-head entries.
43 * For memory efficiency we want to pre-allocate both queues -- which points to ArrayDeque, but that is very
44 * inefficient when entries are removed from the middle. In the typical case we expect the number of in-flight
45 * entries to be an order of magnitude lower than the number of enqueued entries, hence the split.
48 * Note that in transient case of reconnect, when the backend gives us a lower number of maximum in-flight entries
49 * than the previous incarnation, we may end up still moving the pending queue -- but that is a very exceptional
50 * scenario, hence we consciously ignore it to keep the design relatively simple.
53 * This class is not thread-safe, as it is expected to be guarded by {@link AbstractClientConnection}.
55 * @author Robert Varga
57 abstract class TransmitQueue {
58 static final class Halted extends TransmitQueue {
59 // For ConnectingClientConnection.
60 Halted(final int targetDepth) {
64 // For ReconnectingClientConnection.
65 Halted(final TransmitQueue oldQueue, final long now) {
70 int canTransmitCount(final int inflightSize) {
75 Optional<TransmittedConnectionEntry> transmit(final ConnectionEntry entry, final long now) {
76 throw new UnsupportedOperationException("Attempted to transmit on a halted queue");
80 void preComplete(final ResponseEnvelope<?> envelope) {
84 static final class Transmitting extends TransmitQueue {
85 private static final long NOT_SLICING = -1;
87 private final BackendInfo backend;
88 private final MessageSlicer messageSlicer;
89 private long nextTxSequence;
90 private long currentSlicedEnvSequenceId = NOT_SLICING;
92 // For ConnectedClientConnection.
93 Transmitting(final TransmitQueue oldQueue, final int targetDepth, final BackendInfo backend, final long now,
94 final MessageSlicer messageSlicer) {
95 super(oldQueue, targetDepth, now);
96 this.backend = Preconditions.checkNotNull(backend);
97 this.messageSlicer = Preconditions.checkNotNull(messageSlicer);
101 int canTransmitCount(final int inflightSize) {
102 return backend.getMaxMessages() - inflightSize;
106 Optional<TransmittedConnectionEntry> transmit(final ConnectionEntry entry, final long now) {
107 // If we're currently slicing a message we can't send any subsequent requests until slicing completes to
108 // avoid an out-of-sequence request envelope failure on the backend. In this case we return an empty
109 // Optional to indicate the request was not transmitted.
110 if (currentSlicedEnvSequenceId >= 0) {
111 return Optional.empty();
114 final Request<?, ?> request = entry.getRequest();
115 final RequestEnvelope env = new RequestEnvelope(request.toVersion(backend.getVersion()),
116 backend.getSessionId(), nextTxSequence++);
118 if (request instanceof SliceableMessage) {
119 if (messageSlicer.slice(SliceOptions.builder().identifier(request.getTarget())
120 .message(env).replyTo(request.getReplyTo()).sendTo(backend.getActor())
121 .onFailureCallback(t -> env.sendFailure(new RuntimeRequestException(
122 "Failed to slice request " + request, t), 0L)).build())) {
123 // The request was sliced so record the envelope sequence id to prevent transmitting
124 // subsequent requests until slicing completes.
125 currentSlicedEnvSequenceId = env.getTxSequence();
128 backend.getActor().tell(env, ActorRef.noSender());
131 return Optional.of(new TransmittedConnectionEntry(entry, env.getSessionId(),
132 env.getTxSequence(), now));
136 void preComplete(final ResponseEnvelope<?> envelope) {
137 if (envelope.getTxSequence() == currentSlicedEnvSequenceId) {
138 // Slicing completed for the prior request - clear the cached sequence id field to enable subsequent
139 // requests to be transmitted.
140 currentSlicedEnvSequenceId = NOT_SLICING;
145 private static final Logger LOG = LoggerFactory.getLogger(TransmitQueue.class);
147 private final Deque<TransmittedConnectionEntry> inflight = new ArrayDeque<>();
148 private final Deque<ConnectionEntry> pending = new ArrayDeque<>();
149 private final AveragingProgressTracker tracker; // Cannot be just ProgressTracker as we are inheriting limits.
150 private ReconnectForwarder successor;
153 * Construct initial transmitting queue.
155 TransmitQueue(final int targetDepth) {
156 tracker = new AveragingProgressTracker(targetDepth);
160 * Construct new transmitting queue while inheriting timing data from the previous transmit queue instance.
162 TransmitQueue(final TransmitQueue oldQueue, final int targetDepth, final long now) {
163 tracker = new AveragingProgressTracker(oldQueue.tracker, targetDepth, now);
167 * Construct new transmitting queue while inheriting timing and size data from the previous transmit queue instance.
169 TransmitQueue(final TransmitQueue oldQueue, final long now) {
170 tracker = new AveragingProgressTracker(oldQueue.tracker, now);
174 * Cancel the accumulated sum of delays as we expect the new backend to work now.
176 void cancelDebt(final long now) {
177 tracker.cancelDebt(now);
181 * Drain the contents of the connection into a list. This will leave the queue empty and allow further entries
182 * to be added to it during replay. When we set the successor all entries enqueued between when this methods
183 * returns and the successor is set will be replayed to the successor.
185 * @return Collection of entries present in the queue.
187 final Collection<ConnectionEntry> drain() {
188 final Collection<ConnectionEntry> ret = new ArrayDeque<>(inflight.size() + pending.size());
189 ret.addAll(inflight);
196 final long ticksStalling(final long now) {
197 return tracker.ticksStalling(now);
200 final boolean hasSuccessor() {
201 return successor != null;
204 // If a matching request was found, this will track a task was closed.
205 final Optional<TransmittedConnectionEntry> complete(final ResponseEnvelope<?> envelope, final long now) {
206 preComplete(envelope);
208 Optional<TransmittedConnectionEntry> maybeEntry = findMatchingEntry(inflight, envelope);
209 if (maybeEntry == null) {
210 LOG.debug("Request for {} not found in inflight queue, checking pending queue", envelope);
211 maybeEntry = findMatchingEntry(pending, envelope);
214 if (maybeEntry == null || !maybeEntry.isPresent()) {
215 LOG.warn("No request matching {} found, ignoring response", envelope);
216 return Optional.empty();
219 final TransmittedConnectionEntry entry = maybeEntry.get();
220 tracker.closeTask(now, entry.getEnqueuedTicks(), entry.getTxTicks(), envelope.getExecutionTimeNanos());
222 // We have freed up a slot, try to transmit something
225 return Optional.of(entry);
228 final void tryTransmit(final long now) {
229 final int toSend = canTransmitCount(inflight.size());
230 if (toSend > 0 && !pending.isEmpty()) {
231 transmitEntries(toSend, now);
235 private void transmitEntries(final int maxTransmit, final long now) {
236 for (int i = 0; i < maxTransmit; ++i) {
237 final ConnectionEntry e = pending.poll();
238 if (e == null || !transmitEntry(e, now)) {
239 LOG.debug("Queue {} transmitted {} requests", this, i);
244 LOG.debug("Queue {} transmitted {} requests", this, maxTransmit);
247 private boolean transmitEntry(final ConnectionEntry entry, final long now) {
248 LOG.debug("Queue {} transmitting entry {}", this, entry);
249 // We are not thread-safe and are supposed to be externally-guarded,
250 // hence send-before-record should be fine.
251 // This needs to be revisited if the external guards are lowered.
252 final Optional<TransmittedConnectionEntry> maybeTransmitted = transmit(entry, now);
253 if (!maybeTransmitted.isPresent()) {
257 inflight.addLast(maybeTransmitted.get());
261 final long enqueueOrForward(final ConnectionEntry entry, final long now) {
262 if (successor != null) {
263 // This call will pay the enqueuing price, hence the caller does not have to
264 successor.forwardEntry(entry, now);
268 return enqueue(entry, now);
271 final void enqueueOrReplay(final ConnectionEntry entry, final long now) {
272 if (successor != null) {
273 successor.replayEntry(entry, now);
280 * Enqueue an entry, possibly also transmitting it.
282 * @return Delay to be forced on the calling thread, in nanoseconds.
284 private long enqueue(final ConnectionEntry entry, final long now) {
286 // XXX: we should place a guard against incorrect entry sequences:
287 // entry.getEnqueueTicks() should have non-negative difference from the last entry present in the queues
289 // Reserve an entry before we do anything that can fail
290 final long delay = tracker.openTask(now);
293 * This is defensive to make sure we do not do the wrong thing here and reorder messages if we ever happen
294 * to have available send slots and non-empty pending queue.
296 final int toSend = canTransmitCount(inflight.size());
298 LOG.trace("Queue is at capacity, delayed sending of request {}", entry.getRequest());
299 pending.addLast(entry);
303 if (pending.isEmpty()) {
304 if (!transmitEntry(entry, now)) {
305 LOG.debug("Queue {} cannot transmit request {} - delaying it", this, entry.getRequest());
306 pending.addLast(entry);
312 pending.addLast(entry);
313 transmitEntries(toSend, now);
318 * Return the number of entries which can be transmitted assuming the supplied in-flight queue size.
320 abstract int canTransmitCount(int inflightSize);
322 abstract Optional<TransmittedConnectionEntry> transmit(ConnectionEntry entry, long now);
324 abstract void preComplete(ResponseEnvelope<?> envelope);
326 final boolean isEmpty() {
327 return inflight.isEmpty() && pending.isEmpty();
330 final ConnectionEntry peek() {
331 final ConnectionEntry ret = inflight.peek();
336 return pending.peek();
339 final void poison(final RequestException cause) {
340 poisonQueue(inflight, cause);
341 poisonQueue(pending, cause);
344 final void setForwarder(final ReconnectForwarder forwarder, final long now) {
345 Verify.verify(successor == null, "Successor %s already set on connection %s", successor, this);
346 successor = Preconditions.checkNotNull(forwarder);
347 LOG.debug("Connection {} superseded by {}, splicing queue", this, successor);
350 * We need to account for entries which have been added between the time drain() was called and this method
351 * is invoked. Since the old connection is visible during replay and some entries may have completed on the
352 * replay thread, there was an avenue for this to happen.
355 ConnectionEntry entry = inflight.poll();
356 while (entry != null) {
357 successor.replayEntry(entry, now);
358 entry = inflight.poll();
362 entry = pending.poll();
363 while (entry != null) {
364 successor.replayEntry(entry, now);
365 entry = pending.poll();
369 LOG.debug("Connection {} queue spliced {} messages", this, count);
372 final void remove(final long now) {
373 final TransmittedConnectionEntry txe = inflight.poll();
375 final ConnectionEntry entry = pending.pop();
376 tracker.closeTask(now, entry.getEnqueuedTicks(), 0, 0);
378 tracker.closeTask(now, txe.getEnqueuedTicks(), txe.getTxTicks(), 0);
383 Deque<TransmittedConnectionEntry> getInflight() {
388 Deque<ConnectionEntry> getPending() {
393 * We are using tri-state return here to indicate one of three conditions:
394 * - if a matching entry is found, return an Optional containing it
395 * - if a matching entry is not found, but it makes sense to keep looking at other queues, return null
396 * - if a conflicting entry is encountered, indicating we should ignore this request, return an empty Optional
398 @SuppressFBWarnings(value = "NP_OPTIONAL_RETURN_NULL",
399 justification = "Returning null Optional is documented in the API contract.")
400 private static Optional<TransmittedConnectionEntry> findMatchingEntry(final Queue<? extends ConnectionEntry> queue,
401 final ResponseEnvelope<?> envelope) {
402 // Try to find the request in a queue. Responses may legally come back in a different order, hence we need
403 // to use an iterator
404 final Iterator<? extends ConnectionEntry> it = queue.iterator();
405 while (it.hasNext()) {
406 final ConnectionEntry e = it.next();
407 final Request<?, ?> request = e.getRequest();
408 final Response<?, ?> response = envelope.getMessage();
410 // First check for matching target, or move to next entry
411 if (!request.getTarget().equals(response.getTarget())) {
415 // Sanity-check logical sequence, ignore any out-of-order messages
416 if (request.getSequence() != response.getSequence()) {
417 LOG.debug("Expecting sequence {}, ignoring response {}", request.getSequence(), envelope);
418 return Optional.empty();
421 // Check if the entry has (ever) been transmitted
422 if (!(e instanceof TransmittedConnectionEntry)) {
423 return Optional.empty();
426 final TransmittedConnectionEntry te = (TransmittedConnectionEntry) e;
428 // Now check session match
429 if (envelope.getSessionId() != te.getSessionId()) {
430 LOG.debug("Expecting session {}, ignoring response {}", te.getSessionId(), envelope);
431 return Optional.empty();
433 if (envelope.getTxSequence() != te.getTxSequence()) {
434 LOG.warn("Expecting txSequence {}, ignoring response {}", te.getTxSequence(), envelope);
435 return Optional.empty();
438 LOG.debug("Completing request {} with {}", request, envelope);
440 return Optional.of(te);
446 private static void poisonQueue(final Queue<? extends ConnectionEntry> queue, final RequestException cause) {
447 for (ConnectionEntry e : queue) {
448 final Request<?, ?> request = e.getRequest();
449 LOG.trace("Poisoning request {}", request, cause);
450 e.complete(request.toRequestFailure(cause));